CFG.cpp revision d74d69cd5ea01ea77dbee45903d589243d1625d2
1//===--- CFG.cpp - Classes for representing and building CFGs----*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the CFG and CFGBuilder classes for representing and 11// building Control-Flow Graphs (CFGs) from ASTs. 12// 13//===----------------------------------------------------------------------===// 14 15#include "clang/Analysis/Support/SaveAndRestore.h" 16#include "clang/Analysis/CFG.h" 17#include "clang/AST/DeclCXX.h" 18#include "clang/AST/StmtVisitor.h" 19#include "clang/AST/PrettyPrinter.h" 20#include "llvm/Support/GraphWriter.h" 21#include "llvm/Support/Allocator.h" 22#include "llvm/Support/Format.h" 23#include "llvm/ADT/DenseMap.h" 24#include "llvm/ADT/SmallPtrSet.h" 25#include "llvm/ADT/OwningPtr.h" 26 27using namespace clang; 28 29namespace { 30 31static SourceLocation GetEndLoc(Decl* D) { 32 if (VarDecl* VD = dyn_cast<VarDecl>(D)) 33 if (Expr* Ex = VD->getInit()) 34 return Ex->getSourceRange().getEnd(); 35 36 return D->getLocation(); 37} 38 39class AddStmtChoice { 40public: 41 enum Kind { NotAlwaysAdd = 0, 42 AlwaysAdd = 1, 43 AsLValueNotAlwaysAdd = 2, 44 AlwaysAddAsLValue = 3 }; 45 46 AddStmtChoice(Kind kind) : k(kind) {} 47 48 bool alwaysAdd() const { return (unsigned)k & 0x1; } 49 bool asLValue() const { return k >= AlwaysAddAsLValue; } 50 51private: 52 Kind k; 53}; 54 55/// CFGBuilder - This class implements CFG construction from an AST. 56/// The builder is stateful: an instance of the builder should be used to only 57/// construct a single CFG. 58/// 59/// Example usage: 60/// 61/// CFGBuilder builder; 62/// CFG* cfg = builder.BuildAST(stmt1); 63/// 64/// CFG construction is done via a recursive walk of an AST. We actually parse 65/// the AST in reverse order so that the successor of a basic block is 66/// constructed prior to its predecessor. This allows us to nicely capture 67/// implicit fall-throughs without extra basic blocks. 68/// 69class CFGBuilder { 70 ASTContext *Context; 71 llvm::OwningPtr<CFG> cfg; 72 73 CFGBlock* Block; 74 CFGBlock* Succ; 75 CFGBlock* ContinueTargetBlock; 76 CFGBlock* BreakTargetBlock; 77 CFGBlock* SwitchTerminatedBlock; 78 CFGBlock* DefaultCaseBlock; 79 CFGBlock* TryTerminatedBlock; 80 81 // LabelMap records the mapping from Label expressions to their blocks. 82 typedef llvm::DenseMap<LabelStmt*,CFGBlock*> LabelMapTy; 83 LabelMapTy LabelMap; 84 85 // A list of blocks that end with a "goto" that must be backpatched to their 86 // resolved targets upon completion of CFG construction. 87 typedef std::vector<CFGBlock*> BackpatchBlocksTy; 88 BackpatchBlocksTy BackpatchBlocks; 89 90 // A list of labels whose address has been taken (for indirect gotos). 91 typedef llvm::SmallPtrSet<LabelStmt*,5> LabelSetTy; 92 LabelSetTy AddressTakenLabels; 93 94public: 95 explicit CFGBuilder() : cfg(new CFG()), // crew a new CFG 96 Block(NULL), Succ(NULL), 97 ContinueTargetBlock(NULL), BreakTargetBlock(NULL), 98 SwitchTerminatedBlock(NULL), DefaultCaseBlock(NULL), 99 TryTerminatedBlock(NULL) {} 100 101 // buildCFG - Used by external clients to construct the CFG. 102 CFG* buildCFG(const Decl *D, Stmt *Statement, ASTContext *C, bool AddEHEdges, 103 bool AddScopes); 104 105private: 106 // Visitors to walk an AST and construct the CFG. 107 CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc); 108 CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc); 109 CFGBlock *VisitBlockExpr(BlockExpr* E, AddStmtChoice asc); 110 CFGBlock *VisitBreakStmt(BreakStmt *B); 111 CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S); 112 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T); 113 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S); 114 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 115 CFGBlock *VisitCaseStmt(CaseStmt *C); 116 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 117 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 118 CFGBlock *VisitConditionalOperator(ConditionalOperator *C, AddStmtChoice asc); 119 CFGBlock *VisitContinueStmt(ContinueStmt *C); 120 CFGBlock *VisitDeclStmt(DeclStmt *DS); 121 CFGBlock *VisitDeclSubExpr(Decl* D); 122 CFGBlock *VisitDefaultStmt(DefaultStmt *D); 123 CFGBlock *VisitDoStmt(DoStmt *D); 124 CFGBlock *VisitForStmt(ForStmt *F); 125 CFGBlock *VisitGotoStmt(GotoStmt* G); 126 CFGBlock *VisitIfStmt(IfStmt *I); 127 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I); 128 CFGBlock *VisitLabelStmt(LabelStmt *L); 129 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S); 130 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S); 131 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S); 132 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S); 133 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S); 134 CFGBlock *VisitReturnStmt(ReturnStmt* R); 135 CFGBlock *VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, AddStmtChoice asc); 136 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc); 137 CFGBlock *VisitSwitchStmt(SwitchStmt *S); 138 CFGBlock *VisitWhileStmt(WhileStmt *W); 139 140 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd); 141 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc); 142 CFGBlock *VisitChildren(Stmt* S); 143 144 // NYS == Not Yet Supported 145 CFGBlock* NYS() { 146 badCFG = true; 147 return Block; 148 } 149 150 CFGBlock *StartScope(Stmt *S, CFGBlock *B) { 151 if (!AddScopes) 152 return B; 153 154 if (B == 0) 155 B = createBlock(); 156 B->StartScope(S, cfg->getBumpVectorContext()); 157 return B; 158 } 159 160 void EndScope(Stmt *S) { 161 if (!AddScopes) 162 return; 163 164 if (Block == 0) 165 Block = createBlock(); 166 Block->EndScope(S, cfg->getBumpVectorContext()); 167 } 168 169 void autoCreateBlock() { if (!Block) Block = createBlock(); } 170 CFGBlock *createBlock(bool add_successor = true); 171 bool FinishBlock(CFGBlock* B); 172 CFGBlock *addStmt(Stmt *S, AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 173 return Visit(S, asc); 174 } 175 176 void AppendStmt(CFGBlock *B, Stmt *S, 177 AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 178 B->appendStmt(S, cfg->getBumpVectorContext(), asc.asLValue()); 179 } 180 181 void AddSuccessor(CFGBlock *B, CFGBlock *S) { 182 B->addSuccessor(S, cfg->getBumpVectorContext()); 183 } 184 185 /// TryResult - a class representing a variant over the values 186 /// 'true', 'false', or 'unknown'. This is returned by TryEvaluateBool, 187 /// and is used by the CFGBuilder to decide if a branch condition 188 /// can be decided up front during CFG construction. 189 class TryResult { 190 int X; 191 public: 192 TryResult(bool b) : X(b ? 1 : 0) {} 193 TryResult() : X(-1) {} 194 195 bool isTrue() const { return X == 1; } 196 bool isFalse() const { return X == 0; } 197 bool isKnown() const { return X >= 0; } 198 void negate() { 199 assert(isKnown()); 200 X ^= 0x1; 201 } 202 }; 203 204 /// TryEvaluateBool - Try and evaluate the Stmt and return 0 or 1 205 /// if we can evaluate to a known value, otherwise return -1. 206 TryResult TryEvaluateBool(Expr *S) { 207 Expr::EvalResult Result; 208 if (!S->isTypeDependent() && !S->isValueDependent() && 209 S->Evaluate(Result, *Context) && Result.Val.isInt()) 210 return Result.Val.getInt().getBoolValue(); 211 212 return TryResult(); 213 } 214 215 bool badCFG; 216 217 // True iff EH edges on CallExprs should be added to the CFG. 218 bool AddEHEdges; 219 220 // True iff scope start and scope end notes should be added to the CFG. 221 bool AddScopes; 222}; 223 224// FIXME: Add support for dependent-sized array types in C++? 225// Does it even make sense to build a CFG for an uninstantiated template? 226static VariableArrayType* FindVA(Type* t) { 227 while (ArrayType* vt = dyn_cast<ArrayType>(t)) { 228 if (VariableArrayType* vat = dyn_cast<VariableArrayType>(vt)) 229 if (vat->getSizeExpr()) 230 return vat; 231 232 t = vt->getElementType().getTypePtr(); 233 } 234 235 return 0; 236} 237 238/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an 239/// arbitrary statement. Examples include a single expression or a function 240/// body (compound statement). The ownership of the returned CFG is 241/// transferred to the caller. If CFG construction fails, this method returns 242/// NULL. 243CFG* CFGBuilder::buildCFG(const Decl *D, Stmt* Statement, ASTContext* C, 244 bool addehedges, bool AddScopes) { 245 AddEHEdges = addehedges; 246 Context = C; 247 assert(cfg.get()); 248 if (!Statement) 249 return NULL; 250 251 this->AddScopes = AddScopes; 252 badCFG = false; 253 254 // Create an empty block that will serve as the exit block for the CFG. Since 255 // this is the first block added to the CFG, it will be implicitly registered 256 // as the exit block. 257 Succ = createBlock(); 258 assert(Succ == &cfg->getExit()); 259 Block = NULL; // the EXIT block is empty. Create all other blocks lazily. 260 261 // Visit the statements and create the CFG. 262 CFGBlock* B = addStmt(Statement); 263 264 if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) { 265 // FIXME: Add code for base initializers and member initializers. 266 (void)CD; 267 } 268 if (!B) 269 B = Succ; 270 271 if (B) { 272 // Finalize the last constructed block. This usually involves reversing the 273 // order of the statements in the block. 274 if (Block) FinishBlock(B); 275 276 // Backpatch the gotos whose label -> block mappings we didn't know when we 277 // encountered them. 278 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 279 E = BackpatchBlocks.end(); I != E; ++I ) { 280 281 CFGBlock* B = *I; 282 GotoStmt* G = cast<GotoStmt>(B->getTerminator()); 283 LabelMapTy::iterator LI = LabelMap.find(G->getLabel()); 284 285 // If there is no target for the goto, then we are looking at an 286 // incomplete AST. Handle this by not registering a successor. 287 if (LI == LabelMap.end()) continue; 288 289 AddSuccessor(B, LI->second); 290 } 291 292 // Add successors to the Indirect Goto Dispatch block (if we have one). 293 if (CFGBlock* B = cfg->getIndirectGotoBlock()) 294 for (LabelSetTy::iterator I = AddressTakenLabels.begin(), 295 E = AddressTakenLabels.end(); I != E; ++I ) { 296 297 // Lookup the target block. 298 LabelMapTy::iterator LI = LabelMap.find(*I); 299 300 // If there is no target block that contains label, then we are looking 301 // at an incomplete AST. Handle this by not registering a successor. 302 if (LI == LabelMap.end()) continue; 303 304 AddSuccessor(B, LI->second); 305 } 306 307 Succ = B; 308 } 309 310 // Create an empty entry block that has no predecessors. 311 cfg->setEntry(createBlock()); 312 313 return badCFG ? NULL : cfg.take(); 314} 315 316/// createBlock - Used to lazily create blocks that are connected 317/// to the current (global) succcessor. 318CFGBlock* CFGBuilder::createBlock(bool add_successor) { 319 CFGBlock* B = cfg->createBlock(); 320 if (add_successor && Succ) 321 AddSuccessor(B, Succ); 322 return B; 323} 324 325/// FinishBlock - "Finalize" the block by checking if we have a bad CFG. 326bool CFGBuilder::FinishBlock(CFGBlock* B) { 327 if (badCFG) 328 return false; 329 330 assert(B); 331 return true; 332} 333 334/// Visit - Walk the subtree of a statement and add extra 335/// blocks for ternary operators, &&, and ||. We also process "," and 336/// DeclStmts (which may contain nested control-flow). 337CFGBlock* CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) { 338tryAgain: 339 switch (S->getStmtClass()) { 340 default: 341 return VisitStmt(S, asc); 342 343 case Stmt::AddrLabelExprClass: 344 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 345 346 case Stmt::BinaryOperatorClass: 347 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 348 349 case Stmt::BlockExprClass: 350 return VisitBlockExpr(cast<BlockExpr>(S), asc); 351 352 case Stmt::BreakStmtClass: 353 return VisitBreakStmt(cast<BreakStmt>(S)); 354 355 case Stmt::CallExprClass: 356 return VisitCallExpr(cast<CallExpr>(S), asc); 357 358 case Stmt::CaseStmtClass: 359 return VisitCaseStmt(cast<CaseStmt>(S)); 360 361 case Stmt::ChooseExprClass: 362 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 363 364 case Stmt::CompoundStmtClass: 365 return VisitCompoundStmt(cast<CompoundStmt>(S)); 366 367 case Stmt::ConditionalOperatorClass: 368 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 369 370 case Stmt::ContinueStmtClass: 371 return VisitContinueStmt(cast<ContinueStmt>(S)); 372 373 case Stmt::CXXCatchStmtClass: 374 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 375 376 case Stmt::CXXThrowExprClass: 377 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 378 379 case Stmt::CXXTryStmtClass: 380 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 381 382 case Stmt::DeclStmtClass: 383 return VisitDeclStmt(cast<DeclStmt>(S)); 384 385 case Stmt::DefaultStmtClass: 386 return VisitDefaultStmt(cast<DefaultStmt>(S)); 387 388 case Stmt::DoStmtClass: 389 return VisitDoStmt(cast<DoStmt>(S)); 390 391 case Stmt::ForStmtClass: 392 return VisitForStmt(cast<ForStmt>(S)); 393 394 case Stmt::GotoStmtClass: 395 return VisitGotoStmt(cast<GotoStmt>(S)); 396 397 case Stmt::IfStmtClass: 398 return VisitIfStmt(cast<IfStmt>(S)); 399 400 case Stmt::IndirectGotoStmtClass: 401 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 402 403 case Stmt::LabelStmtClass: 404 return VisitLabelStmt(cast<LabelStmt>(S)); 405 406 case Stmt::ObjCAtCatchStmtClass: 407 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 408 409 case Stmt::ObjCAtSynchronizedStmtClass: 410 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 411 412 case Stmt::ObjCAtThrowStmtClass: 413 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 414 415 case Stmt::ObjCAtTryStmtClass: 416 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 417 418 case Stmt::ObjCForCollectionStmtClass: 419 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 420 421 case Stmt::ParenExprClass: 422 S = cast<ParenExpr>(S)->getSubExpr(); 423 goto tryAgain; 424 425 case Stmt::NullStmtClass: 426 return Block; 427 428 case Stmt::ReturnStmtClass: 429 return VisitReturnStmt(cast<ReturnStmt>(S)); 430 431 case Stmt::SizeOfAlignOfExprClass: 432 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 433 434 case Stmt::StmtExprClass: 435 return VisitStmtExpr(cast<StmtExpr>(S), asc); 436 437 case Stmt::SwitchStmtClass: 438 return VisitSwitchStmt(cast<SwitchStmt>(S)); 439 440 case Stmt::WhileStmtClass: 441 return VisitWhileStmt(cast<WhileStmt>(S)); 442 } 443} 444 445CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 446 if (asc.alwaysAdd()) { 447 autoCreateBlock(); 448 AppendStmt(Block, S, asc); 449 } 450 451 return VisitChildren(S); 452} 453 454/// VisitChildren - Visit the children of a Stmt. 455CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 456 CFGBlock *B = Block; 457 for (Stmt::child_iterator I = Terminator->child_begin(), 458 E = Terminator->child_end(); I != E; ++I) { 459 if (*I) B = Visit(*I); 460 } 461 return B; 462} 463 464CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 465 AddStmtChoice asc) { 466 AddressTakenLabels.insert(A->getLabel()); 467 468 if (asc.alwaysAdd()) { 469 autoCreateBlock(); 470 AppendStmt(Block, A, asc); 471 } 472 473 return Block; 474} 475 476CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 477 AddStmtChoice asc) { 478 if (B->isLogicalOp()) { // && or || 479 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 480 AppendStmt(ConfluenceBlock, B, asc); 481 482 if (!FinishBlock(ConfluenceBlock)) 483 return 0; 484 485 // create the block evaluating the LHS 486 CFGBlock* LHSBlock = createBlock(false); 487 LHSBlock->setTerminator(B); 488 489 // create the block evaluating the RHS 490 Succ = ConfluenceBlock; 491 Block = NULL; 492 CFGBlock* RHSBlock = addStmt(B->getRHS()); 493 if (!FinishBlock(RHSBlock)) 494 return 0; 495 496 // See if this is a known constant. 497 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 498 if (KnownVal.isKnown() && (B->getOpcode() == BinaryOperator::LOr)) 499 KnownVal.negate(); 500 501 // Now link the LHSBlock with RHSBlock. 502 if (B->getOpcode() == BinaryOperator::LOr) { 503 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 504 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 505 } else { 506 assert(B->getOpcode() == BinaryOperator::LAnd); 507 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 508 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 509 } 510 511 // Generate the blocks for evaluating the LHS. 512 Block = LHSBlock; 513 return addStmt(B->getLHS()); 514 } 515 else if (B->getOpcode() == BinaryOperator::Comma) { // , 516 autoCreateBlock(); 517 AppendStmt(Block, B, asc); 518 addStmt(B->getRHS()); 519 return addStmt(B->getLHS()); 520 } 521 522 return VisitStmt(B, asc); 523} 524 525CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 526 if (asc.alwaysAdd()) { 527 autoCreateBlock(); 528 AppendStmt(Block, E, asc); 529 } 530 return Block; 531} 532 533CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 534 // "break" is a control-flow statement. Thus we stop processing the current 535 // block. 536 if (Block && !FinishBlock(Block)) 537 return 0; 538 539 // Now create a new block that ends with the break statement. 540 Block = createBlock(false); 541 Block->setTerminator(B); 542 543 // If there is no target for the break, then we are looking at an incomplete 544 // AST. This means that the CFG cannot be constructed. 545 if (BreakTargetBlock) 546 AddSuccessor(Block, BreakTargetBlock); 547 else 548 badCFG = true; 549 550 551 return Block; 552} 553 554static bool CanThrow(Expr *E) { 555 QualType Ty = E->getType(); 556 if (Ty->isFunctionPointerType()) 557 Ty = Ty->getAs<PointerType>()->getPointeeType(); 558 else if (Ty->isBlockPointerType()) 559 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 560 561 const FunctionType *FT = Ty->getAs<FunctionType>(); 562 if (FT) { 563 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 564 if (Proto->hasEmptyExceptionSpec()) 565 return false; 566 } 567 return true; 568} 569 570CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 571 // If this is a call to a no-return function, this stops the block here. 572 bool NoReturn = false; 573 if (getFunctionExtInfo(*C->getCallee()->getType()).getNoReturn()) { 574 NoReturn = true; 575 } 576 577 bool AddEHEdge = false; 578 579 // Languages without exceptions are assumed to not throw. 580 if (Context->getLangOptions().Exceptions) { 581 if (AddEHEdges) 582 AddEHEdge = true; 583 } 584 585 if (FunctionDecl *FD = C->getDirectCallee()) { 586 if (FD->hasAttr<NoReturnAttr>()) 587 NoReturn = true; 588 if (FD->hasAttr<NoThrowAttr>()) 589 AddEHEdge = false; 590 } 591 592 if (!CanThrow(C->getCallee())) 593 AddEHEdge = false; 594 595 if (!NoReturn && !AddEHEdge) 596 return VisitStmt(C, AddStmtChoice::AlwaysAdd); 597 598 if (Block) { 599 Succ = Block; 600 if (!FinishBlock(Block)) 601 return 0; 602 } 603 604 Block = createBlock(!NoReturn); 605 AppendStmt(Block, C, asc); 606 607 if (NoReturn) { 608 // Wire this to the exit block directly. 609 AddSuccessor(Block, &cfg->getExit()); 610 } 611 if (AddEHEdge) { 612 // Add exceptional edges. 613 if (TryTerminatedBlock) 614 AddSuccessor(Block, TryTerminatedBlock); 615 else 616 AddSuccessor(Block, &cfg->getExit()); 617 } 618 619 return VisitChildren(C); 620} 621 622CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 623 AddStmtChoice asc) { 624 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 625 AppendStmt(ConfluenceBlock, C, asc); 626 if (!FinishBlock(ConfluenceBlock)) 627 return 0; 628 629 Succ = ConfluenceBlock; 630 Block = NULL; 631 CFGBlock* LHSBlock = addStmt(C->getLHS()); 632 if (!FinishBlock(LHSBlock)) 633 return 0; 634 635 Succ = ConfluenceBlock; 636 Block = NULL; 637 CFGBlock* RHSBlock = addStmt(C->getRHS()); 638 if (!FinishBlock(RHSBlock)) 639 return 0; 640 641 Block = createBlock(false); 642 // See if this is a known constant. 643 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 644 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 645 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 646 Block->setTerminator(C); 647 return addStmt(C->getCond()); 648} 649 650 651CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 652 EndScope(C); 653 654 CFGBlock* LastBlock = Block; 655 656 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 657 I != E; ++I ) { 658 LastBlock = addStmt(*I); 659 660 if (badCFG) 661 return NULL; 662 } 663 664 LastBlock = StartScope(C, LastBlock); 665 666 return LastBlock; 667} 668 669CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 670 AddStmtChoice asc) { 671 // Create the confluence block that will "merge" the results of the ternary 672 // expression. 673 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 674 AppendStmt(ConfluenceBlock, C, asc); 675 if (!FinishBlock(ConfluenceBlock)) 676 return 0; 677 678 // Create a block for the LHS expression if there is an LHS expression. A 679 // GCC extension allows LHS to be NULL, causing the condition to be the 680 // value that is returned instead. 681 // e.g: x ?: y is shorthand for: x ? x : y; 682 Succ = ConfluenceBlock; 683 Block = NULL; 684 CFGBlock* LHSBlock = NULL; 685 if (C->getLHS()) { 686 LHSBlock = addStmt(C->getLHS()); 687 if (!FinishBlock(LHSBlock)) 688 return 0; 689 Block = NULL; 690 } 691 692 // Create the block for the RHS expression. 693 Succ = ConfluenceBlock; 694 CFGBlock* RHSBlock = addStmt(C->getRHS()); 695 if (!FinishBlock(RHSBlock)) 696 return 0; 697 698 // Create the block that will contain the condition. 699 Block = createBlock(false); 700 701 // See if this is a known constant. 702 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 703 if (LHSBlock) { 704 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 705 } else { 706 if (KnownVal.isFalse()) { 707 // If we know the condition is false, add NULL as the successor for 708 // the block containing the condition. In this case, the confluence 709 // block will have just one predecessor. 710 AddSuccessor(Block, 0); 711 assert(ConfluenceBlock->pred_size() == 1); 712 } else { 713 // If we have no LHS expression, add the ConfluenceBlock as a direct 714 // successor for the block containing the condition. Moreover, we need to 715 // reverse the order of the predecessors in the ConfluenceBlock because 716 // the RHSBlock will have been added to the succcessors already, and we 717 // want the first predecessor to the the block containing the expression 718 // for the case when the ternary expression evaluates to true. 719 AddSuccessor(Block, ConfluenceBlock); 720 assert(ConfluenceBlock->pred_size() == 2); 721 std::reverse(ConfluenceBlock->pred_begin(), 722 ConfluenceBlock->pred_end()); 723 } 724 } 725 726 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 727 Block->setTerminator(C); 728 return addStmt(C->getCond()); 729} 730 731CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 732 autoCreateBlock(); 733 734 if (DS->isSingleDecl()) { 735 AppendStmt(Block, DS); 736 return VisitDeclSubExpr(DS->getSingleDecl()); 737 } 738 739 CFGBlock *B = 0; 740 741 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 742 typedef llvm::SmallVector<Decl*,10> BufTy; 743 BufTy Buf(DS->decl_begin(), DS->decl_end()); 744 745 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 746 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 747 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 748 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 749 750 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 751 // automatically freed with the CFG. 752 DeclGroupRef DG(*I); 753 Decl *D = *I; 754 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 755 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 756 757 // Append the fake DeclStmt to block. 758 AppendStmt(Block, DSNew); 759 B = VisitDeclSubExpr(D); 760 } 761 762 return B; 763} 764 765/// VisitDeclSubExpr - Utility method to add block-level expressions for 766/// initializers in Decls. 767CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 768 assert(Block); 769 770 VarDecl *VD = dyn_cast<VarDecl>(D); 771 772 if (!VD) 773 return Block; 774 775 Expr *Init = VD->getInit(); 776 777 if (Init) { 778 AddStmtChoice::Kind k = 779 VD->getType()->isReferenceType() ? AddStmtChoice::AsLValueNotAlwaysAdd 780 : AddStmtChoice::NotAlwaysAdd; 781 Visit(Init, AddStmtChoice(k)); 782 } 783 784 // If the type of VD is a VLA, then we must process its size expressions. 785 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 786 VA = FindVA(VA->getElementType().getTypePtr())) 787 Block = addStmt(VA->getSizeExpr()); 788 789 return Block; 790} 791 792CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 793 // We may see an if statement in the middle of a basic block, or it may be the 794 // first statement we are processing. In either case, we create a new basic 795 // block. First, we create the blocks for the then...else statements, and 796 // then we create the block containing the if statement. If we were in the 797 // middle of a block, we stop processing that block. That block is then the 798 // implicit successor for the "then" and "else" clauses. 799 800 // The block we were proccessing is now finished. Make it the successor 801 // block. 802 if (Block) { 803 Succ = Block; 804 if (!FinishBlock(Block)) 805 return 0; 806 } 807 808 // Process the false branch. 809 CFGBlock* ElseBlock = Succ; 810 811 if (Stmt* Else = I->getElse()) { 812 SaveAndRestore<CFGBlock*> sv(Succ); 813 814 // NULL out Block so that the recursive call to Visit will 815 // create a new basic block. 816 Block = NULL; 817 ElseBlock = addStmt(Else); 818 819 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 820 ElseBlock = sv.get(); 821 else if (Block) { 822 if (!FinishBlock(ElseBlock)) 823 return 0; 824 } 825 } 826 827 // Process the true branch. 828 CFGBlock* ThenBlock; 829 { 830 Stmt* Then = I->getThen(); 831 assert(Then); 832 SaveAndRestore<CFGBlock*> sv(Succ); 833 Block = NULL; 834 ThenBlock = addStmt(Then); 835 836 if (!ThenBlock) { 837 // We can reach here if the "then" body has all NullStmts. 838 // Create an empty block so we can distinguish between true and false 839 // branches in path-sensitive analyses. 840 ThenBlock = createBlock(false); 841 AddSuccessor(ThenBlock, sv.get()); 842 } else if (Block) { 843 if (!FinishBlock(ThenBlock)) 844 return 0; 845 } 846 } 847 848 // Now create a new block containing the if statement. 849 Block = createBlock(false); 850 851 // Set the terminator of the new block to the If statement. 852 Block->setTerminator(I); 853 854 // See if this is a known constant. 855 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 856 857 // Now add the successors. 858 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 859 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 860 861 // Add the condition as the last statement in the new block. This may create 862 // new blocks as the condition may contain control-flow. Any newly created 863 // blocks will be pointed to be "Block". 864 Block = addStmt(I->getCond()); 865 866 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 867 // and the condition variable initialization to the CFG. 868 if (VarDecl *VD = I->getConditionVariable()) { 869 if (Expr *Init = VD->getInit()) { 870 autoCreateBlock(); 871 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 872 addStmt(Init); 873 } 874 } 875 876 return Block; 877} 878 879 880CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 881 // If we were in the middle of a block we stop processing that block. 882 // 883 // NOTE: If a "return" appears in the middle of a block, this means that the 884 // code afterwards is DEAD (unreachable). We still keep a basic block 885 // for that code; a simple "mark-and-sweep" from the entry block will be 886 // able to report such dead blocks. 887 if (Block) 888 FinishBlock(Block); 889 890 // Create the new block. 891 Block = createBlock(false); 892 893 // The Exit block is the only successor. 894 AddSuccessor(Block, &cfg->getExit()); 895 896 // Add the return statement to the block. This may create new blocks if R 897 // contains control-flow (short-circuit operations). 898 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 899} 900 901CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 902 // Get the block of the labeled statement. Add it to our map. 903 addStmt(L->getSubStmt()); 904 CFGBlock* LabelBlock = Block; 905 906 if (!LabelBlock) // This can happen when the body is empty, i.e. 907 LabelBlock = createBlock(); // scopes that only contains NullStmts. 908 909 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 910 LabelMap[ L ] = LabelBlock; 911 912 // Labels partition blocks, so this is the end of the basic block we were 913 // processing (L is the block's label). Because this is label (and we have 914 // already processed the substatement) there is no extra control-flow to worry 915 // about. 916 LabelBlock->setLabel(L); 917 if (!FinishBlock(LabelBlock)) 918 return 0; 919 920 // We set Block to NULL to allow lazy creation of a new block (if necessary); 921 Block = NULL; 922 923 // This block is now the implicit successor of other blocks. 924 Succ = LabelBlock; 925 926 return LabelBlock; 927} 928 929CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 930 // Goto is a control-flow statement. Thus we stop processing the current 931 // block and create a new one. 932 if (Block) 933 FinishBlock(Block); 934 935 Block = createBlock(false); 936 Block->setTerminator(G); 937 938 // If we already know the mapping to the label block add the successor now. 939 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 940 941 if (I == LabelMap.end()) 942 // We will need to backpatch this block later. 943 BackpatchBlocks.push_back(Block); 944 else 945 AddSuccessor(Block, I->second); 946 947 return Block; 948} 949 950CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 951 CFGBlock* LoopSuccessor = NULL; 952 953 // "for" is a control-flow statement. Thus we stop processing the current 954 // block. 955 if (Block) { 956 if (!FinishBlock(Block)) 957 return 0; 958 LoopSuccessor = Block; 959 } else 960 LoopSuccessor = Succ; 961 962 // Because of short-circuit evaluation, the condition of the loop can span 963 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 964 // evaluate the condition. 965 CFGBlock* ExitConditionBlock = createBlock(false); 966 CFGBlock* EntryConditionBlock = ExitConditionBlock; 967 968 // Set the terminator for the "exit" condition block. 969 ExitConditionBlock->setTerminator(F); 970 971 // Now add the actual condition to the condition block. Because the condition 972 // itself may contain control-flow, new blocks may be created. 973 if (Stmt* C = F->getCond()) { 974 Block = ExitConditionBlock; 975 EntryConditionBlock = addStmt(C); 976 assert(Block == EntryConditionBlock); 977 978 // If this block contains a condition variable, add both the condition 979 // variable and initializer to the CFG. 980 if (VarDecl *VD = F->getConditionVariable()) { 981 if (Expr *Init = VD->getInit()) { 982 autoCreateBlock(); 983 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 984 EntryConditionBlock = addStmt(Init); 985 assert(Block == EntryConditionBlock); 986 } 987 } 988 989 if (Block) { 990 if (!FinishBlock(EntryConditionBlock)) 991 return 0; 992 } 993 } 994 995 // The condition block is the implicit successor for the loop body as well as 996 // any code above the loop. 997 Succ = EntryConditionBlock; 998 999 // See if this is a known constant. 1000 TryResult KnownVal(true); 1001 1002 if (F->getCond()) 1003 KnownVal = TryEvaluateBool(F->getCond()); 1004 1005 // Now create the loop body. 1006 { 1007 assert(F->getBody()); 1008 1009 // Save the current values for Block, Succ, and continue and break targets 1010 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1011 save_continue(ContinueTargetBlock), 1012 save_break(BreakTargetBlock); 1013 1014 // Create a new block to contain the (bottom) of the loop body. 1015 Block = NULL; 1016 1017 if (Stmt* I = F->getInc()) { 1018 // Generate increment code in its own basic block. This is the target of 1019 // continue statements. 1020 Succ = addStmt(I); 1021 } else { 1022 // No increment code. Create a special, empty, block that is used as the 1023 // target block for "looping back" to the start of the loop. 1024 assert(Succ == EntryConditionBlock); 1025 Succ = createBlock(); 1026 } 1027 1028 // Finish up the increment (or empty) block if it hasn't been already. 1029 if (Block) { 1030 assert(Block == Succ); 1031 if (!FinishBlock(Block)) 1032 return 0; 1033 Block = 0; 1034 } 1035 1036 ContinueTargetBlock = Succ; 1037 1038 // The starting block for the loop increment is the block that should 1039 // represent the 'loop target' for looping back to the start of the loop. 1040 ContinueTargetBlock->setLoopTarget(F); 1041 1042 // All breaks should go to the code following the loop. 1043 BreakTargetBlock = LoopSuccessor; 1044 1045 // Now populate the body block, and in the process create new blocks as we 1046 // walk the body of the loop. 1047 CFGBlock* BodyBlock = addStmt(F->getBody()); 1048 1049 if (!BodyBlock) 1050 BodyBlock = ContinueTargetBlock; // can happen for "for (...;...;...) ;" 1051 else if (Block && !FinishBlock(BodyBlock)) 1052 return 0; 1053 1054 // This new body block is a successor to our "exit" condition block. 1055 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1056 } 1057 1058 // Link up the condition block with the code that follows the loop. (the 1059 // false branch). 1060 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1061 1062 // If the loop contains initialization, create a new block for those 1063 // statements. This block can also contain statements that precede the loop. 1064 if (Stmt* I = F->getInit()) { 1065 Block = createBlock(); 1066 return addStmt(I); 1067 } else { 1068 // There is no loop initialization. We are thus basically a while loop. 1069 // NULL out Block to force lazy block construction. 1070 Block = NULL; 1071 Succ = EntryConditionBlock; 1072 return EntryConditionBlock; 1073 } 1074} 1075 1076CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1077 // Objective-C fast enumeration 'for' statements: 1078 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1079 // 1080 // for ( Type newVariable in collection_expression ) { statements } 1081 // 1082 // becomes: 1083 // 1084 // prologue: 1085 // 1. collection_expression 1086 // T. jump to loop_entry 1087 // loop_entry: 1088 // 1. side-effects of element expression 1089 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1090 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1091 // TB: 1092 // statements 1093 // T. jump to loop_entry 1094 // FB: 1095 // what comes after 1096 // 1097 // and 1098 // 1099 // Type existingItem; 1100 // for ( existingItem in expression ) { statements } 1101 // 1102 // becomes: 1103 // 1104 // the same with newVariable replaced with existingItem; the binding works 1105 // the same except that for one ObjCForCollectionStmt::getElement() returns 1106 // a DeclStmt and the other returns a DeclRefExpr. 1107 // 1108 1109 CFGBlock* LoopSuccessor = 0; 1110 1111 if (Block) { 1112 if (!FinishBlock(Block)) 1113 return 0; 1114 LoopSuccessor = Block; 1115 Block = 0; 1116 } else 1117 LoopSuccessor = Succ; 1118 1119 // Build the condition blocks. 1120 CFGBlock* ExitConditionBlock = createBlock(false); 1121 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1122 1123 // Set the terminator for the "exit" condition block. 1124 ExitConditionBlock->setTerminator(S); 1125 1126 // The last statement in the block should be the ObjCForCollectionStmt, which 1127 // performs the actual binding to 'element' and determines if there are any 1128 // more items in the collection. 1129 AppendStmt(ExitConditionBlock, S); 1130 Block = ExitConditionBlock; 1131 1132 // Walk the 'element' expression to see if there are any side-effects. We 1133 // generate new blocks as necesary. We DON'T add the statement by default to 1134 // the CFG unless it contains control-flow. 1135 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1136 if (Block) { 1137 if (!FinishBlock(EntryConditionBlock)) 1138 return 0; 1139 Block = 0; 1140 } 1141 1142 // The condition block is the implicit successor for the loop body as well as 1143 // any code above the loop. 1144 Succ = EntryConditionBlock; 1145 1146 // Now create the true branch. 1147 { 1148 // Save the current values for Succ, continue and break targets. 1149 SaveAndRestore<CFGBlock*> save_Succ(Succ), 1150 save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 1151 1152 BreakTargetBlock = LoopSuccessor; 1153 ContinueTargetBlock = EntryConditionBlock; 1154 1155 CFGBlock* BodyBlock = addStmt(S->getBody()); 1156 1157 if (!BodyBlock) 1158 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1159 else if (Block) { 1160 if (!FinishBlock(BodyBlock)) 1161 return 0; 1162 } 1163 1164 // This new body block is a successor to our "exit" condition block. 1165 AddSuccessor(ExitConditionBlock, BodyBlock); 1166 } 1167 1168 // Link up the condition block with the code that follows the loop. 1169 // (the false branch). 1170 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1171 1172 // Now create a prologue block to contain the collection expression. 1173 Block = createBlock(); 1174 return addStmt(S->getCollection()); 1175} 1176 1177CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1178 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1179 1180 // Inline the body. 1181 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1182 1183 // The sync body starts its own basic block. This makes it a little easier 1184 // for diagnostic clients. 1185 if (SyncBlock) { 1186 if (!FinishBlock(SyncBlock)) 1187 return 0; 1188 1189 Block = 0; 1190 } 1191 1192 Succ = SyncBlock; 1193 1194 // Inline the sync expression. 1195 return addStmt(S->getSynchExpr()); 1196} 1197 1198CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1199 // FIXME 1200 return NYS(); 1201} 1202 1203CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1204 CFGBlock* LoopSuccessor = NULL; 1205 1206 // "while" is a control-flow statement. Thus we stop processing the current 1207 // block. 1208 if (Block) { 1209 if (!FinishBlock(Block)) 1210 return 0; 1211 LoopSuccessor = Block; 1212 } else 1213 LoopSuccessor = Succ; 1214 1215 // Because of short-circuit evaluation, the condition of the loop can span 1216 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1217 // evaluate the condition. 1218 CFGBlock* ExitConditionBlock = createBlock(false); 1219 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1220 1221 // Set the terminator for the "exit" condition block. 1222 ExitConditionBlock->setTerminator(W); 1223 1224 // Now add the actual condition to the condition block. Because the condition 1225 // itself may contain control-flow, new blocks may be created. Thus we update 1226 // "Succ" after adding the condition. 1227 if (Stmt* C = W->getCond()) { 1228 Block = ExitConditionBlock; 1229 EntryConditionBlock = addStmt(C); 1230 assert(Block == EntryConditionBlock); 1231 1232 // If this block contains a condition variable, add both the condition 1233 // variable and initializer to the CFG. 1234 if (VarDecl *VD = W->getConditionVariable()) { 1235 if (Expr *Init = VD->getInit()) { 1236 autoCreateBlock(); 1237 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1238 EntryConditionBlock = addStmt(Init); 1239 assert(Block == EntryConditionBlock); 1240 } 1241 } 1242 1243 if (Block) { 1244 if (!FinishBlock(EntryConditionBlock)) 1245 return 0; 1246 } 1247 } 1248 1249 // The condition block is the implicit successor for the loop body as well as 1250 // any code above the loop. 1251 Succ = EntryConditionBlock; 1252 1253 // See if this is a known constant. 1254 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1255 1256 // Process the loop body. 1257 { 1258 assert(W->getBody()); 1259 1260 // Save the current values for Block, Succ, and continue and break targets 1261 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1262 save_continue(ContinueTargetBlock), 1263 save_break(BreakTargetBlock); 1264 1265 // Create an empty block to represent the transition block for looping back 1266 // to the head of the loop. 1267 Block = 0; 1268 assert(Succ == EntryConditionBlock); 1269 Succ = createBlock(); 1270 Succ->setLoopTarget(W); 1271 ContinueTargetBlock = Succ; 1272 1273 // All breaks should go to the code following the loop. 1274 BreakTargetBlock = LoopSuccessor; 1275 1276 // NULL out Block to force lazy instantiation of blocks for the body. 1277 Block = NULL; 1278 1279 // Create the body. The returned block is the entry to the loop body. 1280 CFGBlock* BodyBlock = addStmt(W->getBody()); 1281 1282 if (!BodyBlock) 1283 BodyBlock = ContinueTargetBlock; // can happen for "while(...) ;" 1284 else if (Block) { 1285 if (!FinishBlock(BodyBlock)) 1286 return 0; 1287 } 1288 1289 // Add the loop body entry as a successor to the condition. 1290 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1291 } 1292 1293 // Link up the condition block with the code that follows the loop. (the 1294 // false branch). 1295 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1296 1297 // There can be no more statements in the condition block since we loop back 1298 // to this block. NULL out Block to force lazy creation of another block. 1299 Block = NULL; 1300 1301 // Return the condition block, which is the dominating block for the loop. 1302 Succ = EntryConditionBlock; 1303 return EntryConditionBlock; 1304} 1305 1306 1307CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1308 // FIXME: For now we pretend that @catch and the code it contains does not 1309 // exit. 1310 return Block; 1311} 1312 1313CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1314 // FIXME: This isn't complete. We basically treat @throw like a return 1315 // statement. 1316 1317 // If we were in the middle of a block we stop processing that block. 1318 if (Block && !FinishBlock(Block)) 1319 return 0; 1320 1321 // Create the new block. 1322 Block = createBlock(false); 1323 1324 // The Exit block is the only successor. 1325 AddSuccessor(Block, &cfg->getExit()); 1326 1327 // Add the statement to the block. This may create new blocks if S contains 1328 // control-flow (short-circuit operations). 1329 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1330} 1331 1332CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1333 // If we were in the middle of a block we stop processing that block. 1334 if (Block && !FinishBlock(Block)) 1335 return 0; 1336 1337 // Create the new block. 1338 Block = createBlock(false); 1339 1340 if (TryTerminatedBlock) 1341 // The current try statement is the only successor. 1342 AddSuccessor(Block, TryTerminatedBlock); 1343 else 1344 // otherwise the Exit block is the only successor. 1345 AddSuccessor(Block, &cfg->getExit()); 1346 1347 // Add the statement to the block. This may create new blocks if S contains 1348 // control-flow (short-circuit operations). 1349 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1350} 1351 1352CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1353 CFGBlock* LoopSuccessor = NULL; 1354 1355 // "do...while" is a control-flow statement. Thus we stop processing the 1356 // current block. 1357 if (Block) { 1358 if (!FinishBlock(Block)) 1359 return 0; 1360 LoopSuccessor = Block; 1361 } else 1362 LoopSuccessor = Succ; 1363 1364 // Because of short-circuit evaluation, the condition of the loop can span 1365 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1366 // evaluate the condition. 1367 CFGBlock* ExitConditionBlock = createBlock(false); 1368 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1369 1370 // Set the terminator for the "exit" condition block. 1371 ExitConditionBlock->setTerminator(D); 1372 1373 // Now add the actual condition to the condition block. Because the condition 1374 // itself may contain control-flow, new blocks may be created. 1375 if (Stmt* C = D->getCond()) { 1376 Block = ExitConditionBlock; 1377 EntryConditionBlock = addStmt(C); 1378 if (Block) { 1379 if (!FinishBlock(EntryConditionBlock)) 1380 return 0; 1381 } 1382 } 1383 1384 // The condition block is the implicit successor for the loop body. 1385 Succ = EntryConditionBlock; 1386 1387 // See if this is a known constant. 1388 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1389 1390 // Process the loop body. 1391 CFGBlock* BodyBlock = NULL; 1392 { 1393 assert(D->getBody()); 1394 1395 // Save the current values for Block, Succ, and continue and break targets 1396 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1397 save_continue(ContinueTargetBlock), 1398 save_break(BreakTargetBlock); 1399 1400 // All continues within this loop should go to the condition block 1401 ContinueTargetBlock = EntryConditionBlock; 1402 1403 // All breaks should go to the code following the loop. 1404 BreakTargetBlock = LoopSuccessor; 1405 1406 // NULL out Block to force lazy instantiation of blocks for the body. 1407 Block = NULL; 1408 1409 // Create the body. The returned block is the entry to the loop body. 1410 BodyBlock = addStmt(D->getBody()); 1411 1412 if (!BodyBlock) 1413 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1414 else if (Block) { 1415 if (!FinishBlock(BodyBlock)) 1416 return 0; 1417 } 1418 1419 // Add an intermediate block between the BodyBlock and the 1420 // ExitConditionBlock to represent the "loop back" transition. Create an 1421 // empty block to represent the transition block for looping back to the 1422 // head of the loop. 1423 // FIXME: Can we do this more efficiently without adding another block? 1424 Block = NULL; 1425 Succ = BodyBlock; 1426 CFGBlock *LoopBackBlock = createBlock(); 1427 LoopBackBlock->setLoopTarget(D); 1428 1429 // Add the loop body entry as a successor to the condition. 1430 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : LoopBackBlock); 1431 } 1432 1433 // Link up the condition block with the code that follows the loop. 1434 // (the false branch). 1435 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1436 1437 // There can be no more statements in the body block(s) since we loop back to 1438 // the body. NULL out Block to force lazy creation of another block. 1439 Block = NULL; 1440 1441 // Return the loop body, which is the dominating block for the loop. 1442 Succ = BodyBlock; 1443 return BodyBlock; 1444} 1445 1446CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1447 // "continue" is a control-flow statement. Thus we stop processing the 1448 // current block. 1449 if (Block && !FinishBlock(Block)) 1450 return 0; 1451 1452 // Now create a new block that ends with the continue statement. 1453 Block = createBlock(false); 1454 Block->setTerminator(C); 1455 1456 // If there is no target for the continue, then we are looking at an 1457 // incomplete AST. This means the CFG cannot be constructed. 1458 if (ContinueTargetBlock) 1459 AddSuccessor(Block, ContinueTargetBlock); 1460 else 1461 badCFG = true; 1462 1463 return Block; 1464} 1465 1466CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 1467 AddStmtChoice asc) { 1468 1469 if (asc.alwaysAdd()) { 1470 autoCreateBlock(); 1471 AppendStmt(Block, E); 1472 } 1473 1474 // VLA types have expressions that must be evaluated. 1475 if (E->isArgumentType()) { 1476 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 1477 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1478 addStmt(VA->getSizeExpr()); 1479 } 1480 1481 return Block; 1482} 1483 1484/// VisitStmtExpr - Utility method to handle (nested) statement 1485/// expressions (a GCC extension). 1486CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 1487 if (asc.alwaysAdd()) { 1488 autoCreateBlock(); 1489 AppendStmt(Block, SE); 1490 } 1491 return VisitCompoundStmt(SE->getSubStmt()); 1492} 1493 1494CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 1495 // "switch" is a control-flow statement. Thus we stop processing the current 1496 // block. 1497 CFGBlock* SwitchSuccessor = NULL; 1498 1499 if (Block) { 1500 if (!FinishBlock(Block)) 1501 return 0; 1502 SwitchSuccessor = Block; 1503 } else SwitchSuccessor = Succ; 1504 1505 // Save the current "switch" context. 1506 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 1507 save_break(BreakTargetBlock), 1508 save_default(DefaultCaseBlock); 1509 1510 // Set the "default" case to be the block after the switch statement. If the 1511 // switch statement contains a "default:", this value will be overwritten with 1512 // the block for that code. 1513 DefaultCaseBlock = SwitchSuccessor; 1514 1515 // Create a new block that will contain the switch statement. 1516 SwitchTerminatedBlock = createBlock(false); 1517 1518 // Now process the switch body. The code after the switch is the implicit 1519 // successor. 1520 Succ = SwitchSuccessor; 1521 BreakTargetBlock = SwitchSuccessor; 1522 1523 // When visiting the body, the case statements should automatically get linked 1524 // up to the switch. We also don't keep a pointer to the body, since all 1525 // control-flow from the switch goes to case/default statements. 1526 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 1527 Block = NULL; 1528 CFGBlock *BodyBlock = addStmt(Terminator->getBody()); 1529 if (Block) { 1530 if (!FinishBlock(BodyBlock)) 1531 return 0; 1532 } 1533 1534 // If we have no "default:" case, the default transition is to the code 1535 // following the switch body. 1536 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 1537 1538 // Add the terminator and condition in the switch block. 1539 SwitchTerminatedBlock->setTerminator(Terminator); 1540 assert(Terminator->getCond() && "switch condition must be non-NULL"); 1541 Block = SwitchTerminatedBlock; 1542 Block = addStmt(Terminator->getCond()); 1543 1544 // Finally, if the SwitchStmt contains a condition variable, add both the 1545 // SwitchStmt and the condition variable initialization to the CFG. 1546 if (VarDecl *VD = Terminator->getConditionVariable()) { 1547 if (Expr *Init = VD->getInit()) { 1548 autoCreateBlock(); 1549 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 1550 addStmt(Init); 1551 } 1552 } 1553 1554 return Block; 1555} 1556 1557CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 1558 // CaseStmts are essentially labels, so they are the first statement in a 1559 // block. 1560 1561 if (CS->getSubStmt()) 1562 addStmt(CS->getSubStmt()); 1563 1564 CFGBlock* CaseBlock = Block; 1565 if (!CaseBlock) 1566 CaseBlock = createBlock(); 1567 1568 // Cases statements partition blocks, so this is the top of the basic block we 1569 // were processing (the "case XXX:" is the label). 1570 CaseBlock->setLabel(CS); 1571 1572 if (!FinishBlock(CaseBlock)) 1573 return 0; 1574 1575 // Add this block to the list of successors for the block with the switch 1576 // statement. 1577 assert(SwitchTerminatedBlock); 1578 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 1579 1580 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1581 Block = NULL; 1582 1583 // This block is now the implicit successor of other blocks. 1584 Succ = CaseBlock; 1585 1586 return CaseBlock; 1587} 1588 1589CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 1590 if (Terminator->getSubStmt()) 1591 addStmt(Terminator->getSubStmt()); 1592 1593 DefaultCaseBlock = Block; 1594 1595 if (!DefaultCaseBlock) 1596 DefaultCaseBlock = createBlock(); 1597 1598 // Default statements partition blocks, so this is the top of the basic block 1599 // we were processing (the "default:" is the label). 1600 DefaultCaseBlock->setLabel(Terminator); 1601 1602 if (!FinishBlock(DefaultCaseBlock)) 1603 return 0; 1604 1605 // Unlike case statements, we don't add the default block to the successors 1606 // for the switch statement immediately. This is done when we finish 1607 // processing the switch statement. This allows for the default case 1608 // (including a fall-through to the code after the switch statement) to always 1609 // be the last successor of a switch-terminated block. 1610 1611 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1612 Block = NULL; 1613 1614 // This block is now the implicit successor of other blocks. 1615 Succ = DefaultCaseBlock; 1616 1617 return DefaultCaseBlock; 1618} 1619 1620CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 1621 // "try"/"catch" is a control-flow statement. Thus we stop processing the 1622 // current block. 1623 CFGBlock* TrySuccessor = NULL; 1624 1625 if (Block) { 1626 if (!FinishBlock(Block)) 1627 return 0; 1628 TrySuccessor = Block; 1629 } else TrySuccessor = Succ; 1630 1631 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 1632 1633 // Create a new block that will contain the try statement. 1634 CFGBlock *NewTryTerminatedBlock = createBlock(false); 1635 // Add the terminator in the try block. 1636 NewTryTerminatedBlock->setTerminator(Terminator); 1637 1638 bool HasCatchAll = false; 1639 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 1640 // The code after the try is the implicit successor. 1641 Succ = TrySuccessor; 1642 CXXCatchStmt *CS = Terminator->getHandler(h); 1643 if (CS->getExceptionDecl() == 0) { 1644 HasCatchAll = true; 1645 } 1646 Block = NULL; 1647 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 1648 if (CatchBlock == 0) 1649 return 0; 1650 // Add this block to the list of successors for the block with the try 1651 // statement. 1652 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 1653 } 1654 if (!HasCatchAll) { 1655 if (PrevTryTerminatedBlock) 1656 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 1657 else 1658 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 1659 } 1660 1661 // The code after the try is the implicit successor. 1662 Succ = TrySuccessor; 1663 1664 // Save the current "try" context. 1665 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 1666 TryTerminatedBlock = NewTryTerminatedBlock; 1667 1668 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 1669 Block = NULL; 1670 Block = addStmt(Terminator->getTryBlock()); 1671 return Block; 1672} 1673 1674CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 1675 // CXXCatchStmt are treated like labels, so they are the first statement in a 1676 // block. 1677 1678 if (CS->getHandlerBlock()) 1679 addStmt(CS->getHandlerBlock()); 1680 1681 CFGBlock* CatchBlock = Block; 1682 if (!CatchBlock) 1683 CatchBlock = createBlock(); 1684 1685 CatchBlock->setLabel(CS); 1686 1687 if (!FinishBlock(CatchBlock)) 1688 return 0; 1689 1690 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1691 Block = NULL; 1692 1693 return CatchBlock; 1694} 1695 1696CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1697 // Lazily create the indirect-goto dispatch block if there isn't one already. 1698 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 1699 1700 if (!IBlock) { 1701 IBlock = createBlock(false); 1702 cfg->setIndirectGotoBlock(IBlock); 1703 } 1704 1705 // IndirectGoto is a control-flow statement. Thus we stop processing the 1706 // current block and create a new one. 1707 if (Block && !FinishBlock(Block)) 1708 return 0; 1709 1710 Block = createBlock(false); 1711 Block->setTerminator(I); 1712 AddSuccessor(Block, IBlock); 1713 return addStmt(I->getTarget()); 1714} 1715 1716} // end anonymous namespace 1717 1718/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 1719/// no successors or predecessors. If this is the first block created in the 1720/// CFG, it is automatically set to be the Entry and Exit of the CFG. 1721CFGBlock* CFG::createBlock() { 1722 bool first_block = begin() == end(); 1723 1724 // Create the block. 1725 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 1726 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 1727 Blocks.push_back(Mem, BlkBVC); 1728 1729 // If this is the first block, set it as the Entry and Exit. 1730 if (first_block) 1731 Entry = Exit = &back(); 1732 1733 // Return the block. 1734 return &back(); 1735} 1736 1737/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 1738/// CFG is returned to the caller. 1739CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 1740 bool AddEHEdges, bool AddScopes) { 1741 CFGBuilder Builder; 1742 return Builder.buildCFG(D, Statement, C, AddEHEdges, AddScopes); 1743} 1744 1745//===----------------------------------------------------------------------===// 1746// CFG: Queries for BlkExprs. 1747//===----------------------------------------------------------------------===// 1748 1749namespace { 1750 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 1751} 1752 1753static void FindSubExprAssignments(Stmt *S, 1754 llvm::SmallPtrSet<Expr*,50>& Set) { 1755 if (!S) 1756 return; 1757 1758 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 1759 Stmt *child = *I; 1760 if (!child) 1761 continue; 1762 1763 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 1764 if (B->isAssignmentOp()) Set.insert(B); 1765 1766 FindSubExprAssignments(child, Set); 1767 } 1768} 1769 1770static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 1771 BlkExprMapTy* M = new BlkExprMapTy(); 1772 1773 // Look for assignments that are used as subexpressions. These are the only 1774 // assignments that we want to *possibly* register as a block-level 1775 // expression. Basically, if an assignment occurs both in a subexpression and 1776 // at the block-level, it is a block-level expression. 1777 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 1778 1779 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 1780 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1781 FindSubExprAssignments(*BI, SubExprAssignments); 1782 1783 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 1784 1785 // Iterate over the statements again on identify the Expr* and Stmt* at the 1786 // block-level that are block-level expressions. 1787 1788 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1789 if (Expr* Exp = dyn_cast<Expr>(*BI)) { 1790 1791 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 1792 // Assignment expressions that are not nested within another 1793 // expression are really "statements" whose value is never used by 1794 // another expression. 1795 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 1796 continue; 1797 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 1798 // Special handling for statement expressions. The last statement in 1799 // the statement expression is also a block-level expr. 1800 const CompoundStmt* C = Terminator->getSubStmt(); 1801 if (!C->body_empty()) { 1802 unsigned x = M->size(); 1803 (*M)[C->body_back()] = x; 1804 } 1805 } 1806 1807 unsigned x = M->size(); 1808 (*M)[Exp] = x; 1809 } 1810 1811 // Look at terminators. The condition is a block-level expression. 1812 1813 Stmt* S = (*I)->getTerminatorCondition(); 1814 1815 if (S && M->find(S) == M->end()) { 1816 unsigned x = M->size(); 1817 (*M)[S] = x; 1818 } 1819 } 1820 1821 return M; 1822} 1823 1824CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 1825 assert(S != NULL); 1826 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 1827 1828 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 1829 BlkExprMapTy::iterator I = M->find(S); 1830 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 1831} 1832 1833unsigned CFG::getNumBlkExprs() { 1834 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 1835 return M->size(); 1836 else { 1837 // We assume callers interested in the number of BlkExprs will want 1838 // the map constructed if it doesn't already exist. 1839 BlkExprMap = (void*) PopulateBlkExprMap(*this); 1840 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 1841 } 1842} 1843 1844//===----------------------------------------------------------------------===// 1845// Cleanup: CFG dstor. 1846//===----------------------------------------------------------------------===// 1847 1848CFG::~CFG() { 1849 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 1850} 1851 1852//===----------------------------------------------------------------------===// 1853// CFG pretty printing 1854//===----------------------------------------------------------------------===// 1855 1856namespace { 1857 1858class StmtPrinterHelper : public PrinterHelper { 1859 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 1860 StmtMapTy StmtMap; 1861 signed CurrentBlock; 1862 unsigned CurrentStmt; 1863 const LangOptions &LangOpts; 1864public: 1865 1866 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 1867 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 1868 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 1869 unsigned j = 1; 1870 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 1871 BI != BEnd; ++BI, ++j ) 1872 StmtMap[*BI] = std::make_pair((*I)->getBlockID(),j); 1873 } 1874 } 1875 1876 virtual ~StmtPrinterHelper() {} 1877 1878 const LangOptions &getLangOpts() const { return LangOpts; } 1879 void setBlockID(signed i) { CurrentBlock = i; } 1880 void setStmtID(unsigned i) { CurrentStmt = i; } 1881 1882 virtual bool handledStmt(Stmt* Terminator, llvm::raw_ostream& OS) { 1883 1884 StmtMapTy::iterator I = StmtMap.find(Terminator); 1885 1886 if (I == StmtMap.end()) 1887 return false; 1888 1889 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 1890 && I->second.second == CurrentStmt) { 1891 return false; 1892 } 1893 1894 OS << "[B" << I->second.first << "." << I->second.second << "]"; 1895 return true; 1896 } 1897}; 1898} // end anonymous namespace 1899 1900 1901namespace { 1902class CFGBlockTerminatorPrint 1903 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 1904 1905 llvm::raw_ostream& OS; 1906 StmtPrinterHelper* Helper; 1907 PrintingPolicy Policy; 1908public: 1909 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 1910 const PrintingPolicy &Policy) 1911 : OS(os), Helper(helper), Policy(Policy) {} 1912 1913 void VisitIfStmt(IfStmt* I) { 1914 OS << "if "; 1915 I->getCond()->printPretty(OS,Helper,Policy); 1916 } 1917 1918 // Default case. 1919 void VisitStmt(Stmt* Terminator) { 1920 Terminator->printPretty(OS, Helper, Policy); 1921 } 1922 1923 void VisitForStmt(ForStmt* F) { 1924 OS << "for (" ; 1925 if (F->getInit()) 1926 OS << "..."; 1927 OS << "; "; 1928 if (Stmt* C = F->getCond()) 1929 C->printPretty(OS, Helper, Policy); 1930 OS << "; "; 1931 if (F->getInc()) 1932 OS << "..."; 1933 OS << ")"; 1934 } 1935 1936 void VisitWhileStmt(WhileStmt* W) { 1937 OS << "while " ; 1938 if (Stmt* C = W->getCond()) 1939 C->printPretty(OS, Helper, Policy); 1940 } 1941 1942 void VisitDoStmt(DoStmt* D) { 1943 OS << "do ... while "; 1944 if (Stmt* C = D->getCond()) 1945 C->printPretty(OS, Helper, Policy); 1946 } 1947 1948 void VisitSwitchStmt(SwitchStmt* Terminator) { 1949 OS << "switch "; 1950 Terminator->getCond()->printPretty(OS, Helper, Policy); 1951 } 1952 1953 void VisitCXXTryStmt(CXXTryStmt* CS) { 1954 OS << "try ..."; 1955 } 1956 1957 void VisitConditionalOperator(ConditionalOperator* C) { 1958 C->getCond()->printPretty(OS, Helper, Policy); 1959 OS << " ? ... : ..."; 1960 } 1961 1962 void VisitChooseExpr(ChooseExpr* C) { 1963 OS << "__builtin_choose_expr( "; 1964 C->getCond()->printPretty(OS, Helper, Policy); 1965 OS << " )"; 1966 } 1967 1968 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1969 OS << "goto *"; 1970 I->getTarget()->printPretty(OS, Helper, Policy); 1971 } 1972 1973 void VisitBinaryOperator(BinaryOperator* B) { 1974 if (!B->isLogicalOp()) { 1975 VisitExpr(B); 1976 return; 1977 } 1978 1979 B->getLHS()->printPretty(OS, Helper, Policy); 1980 1981 switch (B->getOpcode()) { 1982 case BinaryOperator::LOr: 1983 OS << " || ..."; 1984 return; 1985 case BinaryOperator::LAnd: 1986 OS << " && ..."; 1987 return; 1988 default: 1989 assert(false && "Invalid logical operator."); 1990 } 1991 } 1992 1993 void VisitExpr(Expr* E) { 1994 E->printPretty(OS, Helper, Policy); 1995 } 1996}; 1997} // end anonymous namespace 1998 1999 2000static void print_stmt(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2001 const CFGElement &E) { 2002 Stmt *Terminator = E; 2003 2004 if (E.asStartScope()) { 2005 OS << "start scope\n"; 2006 return; 2007 } 2008 if (E.asEndScope()) { 2009 OS << "end scope\n"; 2010 return; 2011 } 2012 2013 if (Helper) { 2014 // special printing for statement-expressions. 2015 if (StmtExpr* SE = dyn_cast<StmtExpr>(Terminator)) { 2016 CompoundStmt* Sub = SE->getSubStmt(); 2017 2018 if (Sub->child_begin() != Sub->child_end()) { 2019 OS << "({ ... ; "; 2020 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2021 OS << " })\n"; 2022 return; 2023 } 2024 } 2025 2026 // special printing for comma expressions. 2027 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Terminator)) { 2028 if (B->getOpcode() == BinaryOperator::Comma) { 2029 OS << "... , "; 2030 Helper->handledStmt(B->getRHS(),OS); 2031 OS << '\n'; 2032 return; 2033 } 2034 } 2035 } 2036 2037 Terminator->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2038 2039 // Expressions need a newline. 2040 if (isa<Expr>(Terminator)) OS << '\n'; 2041} 2042 2043static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2044 const CFGBlock& B, 2045 StmtPrinterHelper* Helper, bool print_edges) { 2046 2047 if (Helper) Helper->setBlockID(B.getBlockID()); 2048 2049 // Print the header. 2050 OS << "\n [ B" << B.getBlockID(); 2051 2052 if (&B == &cfg->getEntry()) 2053 OS << " (ENTRY) ]\n"; 2054 else if (&B == &cfg->getExit()) 2055 OS << " (EXIT) ]\n"; 2056 else if (&B == cfg->getIndirectGotoBlock()) 2057 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2058 else 2059 OS << " ]\n"; 2060 2061 // Print the label of this block. 2062 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2063 2064 if (print_edges) 2065 OS << " "; 2066 2067 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2068 OS << L->getName(); 2069 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2070 OS << "case "; 2071 C->getLHS()->printPretty(OS, Helper, 2072 PrintingPolicy(Helper->getLangOpts())); 2073 if (C->getRHS()) { 2074 OS << " ... "; 2075 C->getRHS()->printPretty(OS, Helper, 2076 PrintingPolicy(Helper->getLangOpts())); 2077 } 2078 } else if (isa<DefaultStmt>(Label)) 2079 OS << "default"; 2080 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2081 OS << "catch ("; 2082 if (CS->getExceptionDecl()) 2083 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2084 0); 2085 else 2086 OS << "..."; 2087 OS << ")"; 2088 2089 } else 2090 assert(false && "Invalid label statement in CFGBlock."); 2091 2092 OS << ":\n"; 2093 } 2094 2095 // Iterate through the statements in the block and print them. 2096 unsigned j = 1; 2097 2098 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2099 I != E ; ++I, ++j ) { 2100 2101 // Print the statement # in the basic block and the statement itself. 2102 if (print_edges) 2103 OS << " "; 2104 2105 OS << llvm::format("%3d", j) << ": "; 2106 2107 if (Helper) 2108 Helper->setStmtID(j); 2109 2110 print_stmt(OS,Helper,*I); 2111 } 2112 2113 // Print the terminator of this block. 2114 if (B.getTerminator()) { 2115 if (print_edges) 2116 OS << " "; 2117 2118 OS << " T: "; 2119 2120 if (Helper) Helper->setBlockID(-1); 2121 2122 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2123 PrintingPolicy(Helper->getLangOpts())); 2124 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator())); 2125 OS << '\n'; 2126 } 2127 2128 if (print_edges) { 2129 // Print the predecessors of this block. 2130 OS << " Predecessors (" << B.pred_size() << "):"; 2131 unsigned i = 0; 2132 2133 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2134 I != E; ++I, ++i) { 2135 2136 if (i == 8 || (i-8) == 0) 2137 OS << "\n "; 2138 2139 OS << " B" << (*I)->getBlockID(); 2140 } 2141 2142 OS << '\n'; 2143 2144 // Print the successors of this block. 2145 OS << " Successors (" << B.succ_size() << "):"; 2146 i = 0; 2147 2148 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2149 I != E; ++I, ++i) { 2150 2151 if (i == 8 || (i-8) % 10 == 0) 2152 OS << "\n "; 2153 2154 if (*I) 2155 OS << " B" << (*I)->getBlockID(); 2156 else 2157 OS << " NULL"; 2158 } 2159 2160 OS << '\n'; 2161 } 2162} 2163 2164 2165/// dump - A simple pretty printer of a CFG that outputs to stderr. 2166void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2167 2168/// print - A simple pretty printer of a CFG that outputs to an ostream. 2169void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2170 StmtPrinterHelper Helper(this, LO); 2171 2172 // Print the entry block. 2173 print_block(OS, this, getEntry(), &Helper, true); 2174 2175 // Iterate through the CFGBlocks and print them one by one. 2176 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2177 // Skip the entry block, because we already printed it. 2178 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2179 continue; 2180 2181 print_block(OS, this, **I, &Helper, true); 2182 } 2183 2184 // Print the exit block. 2185 print_block(OS, this, getExit(), &Helper, true); 2186 OS.flush(); 2187} 2188 2189/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2190void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2191 print(llvm::errs(), cfg, LO); 2192} 2193 2194/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2195/// Generally this will only be called from CFG::print. 2196void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2197 const LangOptions &LO) const { 2198 StmtPrinterHelper Helper(cfg, LO); 2199 print_block(OS, cfg, *this, &Helper, true); 2200} 2201 2202/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2203void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2204 const LangOptions &LO) const { 2205 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2206 TPrinter.Visit(const_cast<Stmt*>(getTerminator())); 2207} 2208 2209Stmt* CFGBlock::getTerminatorCondition() { 2210 2211 if (!Terminator) 2212 return NULL; 2213 2214 Expr* E = NULL; 2215 2216 switch (Terminator->getStmtClass()) { 2217 default: 2218 break; 2219 2220 case Stmt::ForStmtClass: 2221 E = cast<ForStmt>(Terminator)->getCond(); 2222 break; 2223 2224 case Stmt::WhileStmtClass: 2225 E = cast<WhileStmt>(Terminator)->getCond(); 2226 break; 2227 2228 case Stmt::DoStmtClass: 2229 E = cast<DoStmt>(Terminator)->getCond(); 2230 break; 2231 2232 case Stmt::IfStmtClass: 2233 E = cast<IfStmt>(Terminator)->getCond(); 2234 break; 2235 2236 case Stmt::ChooseExprClass: 2237 E = cast<ChooseExpr>(Terminator)->getCond(); 2238 break; 2239 2240 case Stmt::IndirectGotoStmtClass: 2241 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2242 break; 2243 2244 case Stmt::SwitchStmtClass: 2245 E = cast<SwitchStmt>(Terminator)->getCond(); 2246 break; 2247 2248 case Stmt::ConditionalOperatorClass: 2249 E = cast<ConditionalOperator>(Terminator)->getCond(); 2250 break; 2251 2252 case Stmt::BinaryOperatorClass: // '&&' and '||' 2253 E = cast<BinaryOperator>(Terminator)->getLHS(); 2254 break; 2255 2256 case Stmt::ObjCForCollectionStmtClass: 2257 return Terminator; 2258 } 2259 2260 return E ? E->IgnoreParens() : NULL; 2261} 2262 2263bool CFGBlock::hasBinaryBranchTerminator() const { 2264 2265 if (!Terminator) 2266 return false; 2267 2268 Expr* E = NULL; 2269 2270 switch (Terminator->getStmtClass()) { 2271 default: 2272 return false; 2273 2274 case Stmt::ForStmtClass: 2275 case Stmt::WhileStmtClass: 2276 case Stmt::DoStmtClass: 2277 case Stmt::IfStmtClass: 2278 case Stmt::ChooseExprClass: 2279 case Stmt::ConditionalOperatorClass: 2280 case Stmt::BinaryOperatorClass: 2281 return true; 2282 } 2283 2284 return E ? E->IgnoreParens() : NULL; 2285} 2286 2287 2288//===----------------------------------------------------------------------===// 2289// CFG Graphviz Visualization 2290//===----------------------------------------------------------------------===// 2291 2292 2293#ifndef NDEBUG 2294static StmtPrinterHelper* GraphHelper; 2295#endif 2296 2297void CFG::viewCFG(const LangOptions &LO) const { 2298#ifndef NDEBUG 2299 StmtPrinterHelper H(this, LO); 2300 GraphHelper = &H; 2301 llvm::ViewGraph(this,"CFG"); 2302 GraphHelper = NULL; 2303#endif 2304} 2305 2306namespace llvm { 2307template<> 2308struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 2309 2310 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 2311 2312 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 2313 2314#ifndef NDEBUG 2315 std::string OutSStr; 2316 llvm::raw_string_ostream Out(OutSStr); 2317 print_block(Out,Graph, *Node, GraphHelper, false); 2318 std::string& OutStr = Out.str(); 2319 2320 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 2321 2322 // Process string output to make it nicer... 2323 for (unsigned i = 0; i != OutStr.length(); ++i) 2324 if (OutStr[i] == '\n') { // Left justify 2325 OutStr[i] = '\\'; 2326 OutStr.insert(OutStr.begin()+i+1, 'l'); 2327 } 2328 2329 return OutStr; 2330#else 2331 return ""; 2332#endif 2333 } 2334}; 2335} // end namespace llvm 2336